SANDRA REGINA DAMATTO

SANDRA REGINA DAMATTO

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Natural and artificial nuclides in Salesópolis reservoir
2019 - SILVA, P.S.C.; SEMMLER, R.; ZAHN, G.S.; ROCHA, F.R.; DAMATTO, S.R.; FAVARO, D.I.T.
Natural radioactivity is ubiquitous in the environment mainly due to the presence of the nuclides from the ura-nium and thorium series and 40K. Although in the South Hemisphere nuclear tests have been fewer in number than that in the North, artificial radionuclides can also be found spread at ground level. In this study, the activity concentrations of natural nuclides from the uranium and thorium series, 40K and the artificial 137Cs were deter-mined in a sediment core with 42 cm depth collected in the middle of the Salesópolis reservoir, located in the Metropolitan Region of São Paulo city (SPMR). The Usina Parque Rio Tietê reservoir belongs to the Alto do Tietê system for the capture, storage and treatment of water for SPMR. Therefore, the quality of the water and sediments of this dam is of great importance. The activity concentrations were measured by gamma spectrome-try. Samples were measured and saved at regular intervals at a maximum of 160 000 seconds. The gross area were determined for each peak and plotted against time and the counting rate was obtained by the slope of the curve. Background and reference materials were also counted and treated in the same way. Results showed that 226Ra varied from 45 to 116 Bq kg-1; 228Ra, from 80 to 165 Bq kg-1; 40K, from 155 to 1 187 Bq kg-1 and 137Cs varied from 0.3 to 7 Bq kg-1. The methodology applied for determining low levels of 137Cs in sediment proved to be effi-cient and reproducible.
Biogeochemical diversity, O2-supersaturation and hot moments of GHG emissions from shallow alkaline lakes in the Pantanal of Nhecolândia, Brazil
2018 - BARBIERO, LAURENT; SIQUEIRA NETO, MARCOS; BRAZ, ROSANGELA R.; CARMO, JANAINA B. do; REZENDE FILHO, ARY T.; MAZZI, EDMAR; FERNANDES, FERNANDO A.; DAMATTO, SANDRA R.; CAMARGO, PLINIO B. de
Nhecolândia is a vast sub-region of the Pantanal wetland in Brazil with great diversity in surface water chemistry evolving in a sodic alkaline pathway under the influence of evaporation. In this region, > 15,000 shallow lakes are likely to contribute an enormous quantity of greenhouse gas to the atmosphere, but the diversity of the biogeochemical scenarios and their variability in time and space is a major challenge to estimate the regional contribution. From 4 selected alkaline lakes, we compiled measurements of the physico-chemical characteristics of water and sediments, gas fluxes in floating chambers, and sedimentation rates to illustrate this diversity. Although these lakes have a similar chemical composition, the results confirm a difference between the black-water and green-water alkaline lakes, corresponding to distinct biogeochemical functioning. This difference does not appear to affect lake sedimentation rates, but is reflected in gas emissions. Black-water lakes are CO2 and CH4 sources, with fairly constant emissions throughout the seasons. Annual carbon dioxide and methane emissions approach 0.86 mol m− 2 y− 1 and 0.07 mol m− 2 y− 1, respectively, and no clear trend towards N2O capture or emission was observed. By contrast, green-water lakes are CO2 and N2O sinks but important CH4 sources with fluxes varying significantly throughout the seasons, depending on the magnitude of the phytoplankton bloom. The results highlight important daily and seasonal variations in gas fluxes, and in particular a hot moments for methane emissions, when the O2-supersaturation is reached during the afternoon under extreme bloom and sunny weather conditions, provoking an abrupt O2 purging of the lakes. Taking into account the seasonal variability, annual methane emissions are around 10.2 mol m− 2 y− 1, i.e., much higher than reported in previous studies for alkaline lakes in Nhecolândia. Carbon dioxide and nitrous oxide consumption is estimated about 1.9 mol m− 2 y− 1 and 0.73 mmol m− 2 y− 1, respectively. However, these balances must be better constrained with systematic and targeted measurements throughout the seasons.
Natural and artificial nuclides in Salesópolis reservoir by gamma spectrometry
2017 - SILVA, PAULO S.C.; SEMMLER, RENATO; ZAHN, GUILHERME S.; ROCHA, FLAVIO R.; DAMATTO, SANDRA R.; FAVARO, DEBORAH I.T.
Avaliação da concentração de sup(210)Pb e sup(210)Po na Nicotina tabacum L. - variedade virginia - cultivada no Brasil
2015 - SANTOS, THIAGO O.; DAMATTO, SANDRA R.
Metal distribution in sediment cores from São Paulo State Coast, Brazil
2011 - SILVA, PAULO S.C.; DAMATTO, SANDRA R.; MANDONADO, CAIO; FAVARO, DEBORAH I.T.; MAZZILLI, BARBARA P.